Adipose or lipid-rich tissue, which is also sometimes referred to as “fat” or “fatty tissue”, is a common cosmetic and surgical problem, and excessive body fat may also pose certain other health risks. Many factors, including heredity, glandular function, nutrition and lifestyle affect both the extent and location of body fat. Despite dieting and exercise, many people cannot lose fat, particularly in certain areas. Heretofore, liposuction, a procedure in which fat is removed by a suction cannula under local anesthesia, or other forms of fat excision have been used. Fat also occurs in pads on the face and neck and small area local liposuction has sometimes been performed in these areas. However, liposuction is an invasive surgical procedure and presents all of the disadvantages and risks to the patient involved in such a procedure, including scars at the sites of entry into skin. Another problem with liposuction is that it is not selective in only removing unwanted fat, but also rips out tissue in the path of the liposuction hose, including the collagen supporting structure holding the patient's skin in place. This can result in cosmetically unattractive sagging skin in the treated area, in addition to significant pain to the patient both during and after the procedure, risk of infection and other potential problems. The trauma caused by extreme liposuction has in some cases even resulted in the death of the patient. Further, while liposuction can be used for the removal of deep fat, it is significantly less effective for removing fat at a superficial level of subcutaneous fat just below the dermis. Such removal is desirable in some cases because it is less traumatic to the patient. However, it is difficult to do with a liposuction cannula without scratching the dermis, damage to the dermis not healing readily, and attempts to perform surface liposuction also result in an uneven removal of fat which leaves an esthetically unattractive patterning on the patient's skin. Therefore, while liposuction is still used extensively for the removal of excess fat, it is not a desirable procedure.
Fat is also a problem in various surgical procedures where it may be difficult to locate vessels, organs or other anatomical elements on which surgery is to be performed when these elements are covered in fat, and it may be difficult to close surgical openings in such elements. Performing surgery on vessels, organs or other elements covered by fat is therefore risky and current procedures for removing such fat to facilitate surgical procedures have significant limitations. Of particular concern is mesenteric fat which is a common hindrance in laparoscopic surgery. With the current trend of making surgical procedures less invasive by inserting tools through a small surgical opening, the removal of fat in the region where a surgical procedure is being performed, utilizing a tool consistent with such surgical procedures, so as to facilitate remote viewing of the anatomical element being treated/operated on is therefore becoming increasingly important.
In addition, a major problem for teenagers and others is acne which originates at least in part from obstruction of outflow from a sebaceous gland. Certain drug treatments for acne operate through a mechanism of decreasing sebaceous gland output. Destruction, removal, or unblocking of the sebaceous gland, which gland contains lipid-rich tissue, in a non-invasive manner are therefore desirable alternatives for treatment or prevention of acne.
Another related problem is the removal of unwanted hair, and in particular the long-term or permanent removal of such hair by the damage or destruction of the hair follicle. Many techniques have been employed over the years for this treatment, including electrolysis, waxing and treatments with various forms of radiation, including light. However, electrolysis is slow and both electrolysis and waxing are painful to the patient and seldom permanent. Various radiation treatments, particularly those involving light, work more effectively for patients having darker hair than for patients with light hair and various proposals have been made over the years to add a chromophore in some way to the follicle to facilitate such treatments. The use of such artificial chromphores has not heretofore been particularly successful.
Other related problems involve either removing fat, for example in the stratum corneum, under certain conditions, for example when a pressure injection is to be given, selectively porating cells having lipid-rich walls to permit substances, for example therapeutic agents, to enter the cells or to permit the removal of wanted or unwanted substances therefrom or to otherwise heat or destroy lipid-rich tissue for various therapeutic purposes.
While lasers or other light sources have been proposed in the past for heating, removal, destruction (for example killing), photocoagulation, eradication or otherwise treating (hereinafter collectively referred to as “treating” or “treatment”) of lipid-rich tissue such as subcutaneous fat, the lasers proposed for such procedures have operated at a wavelength where lipid-rich tissue has an absorption coefficient which is generally significantly less then than that for water. This presents several problems. First, lipid-rich tissue is radiation heated as a result of absorption in the tissue of radiation energy. Therefore, for wavelengths at which lipid-rich tissue does not absorb the radiation strongly, large amounts of energy must be applied to the tissue in order to obtain the requisite heating. However, in addition to significantly increasing the cost of the procedure, the need for high energy poses a danger of damage to surrounding tissue or the tissue through which the radiation passes, particularly since most such tissue is primarily composed of water which absorbs the radiant energy much more at these wavelengths.
This is a particular problem for subcutaneous fat which generally starts at a depth of at least 1 to 4 mm into a patient's skin, and may be deeper for some individuals or some body areas. Therefore, in order for the radiation to target to the subcutaneous fat to cause selective heating or destruction thereof, it must pass through several millimeters of tissue formed primarily of water. Since water preferentially absorbs at these wavelengths, most of the incident radiation is absorbed in the skin prior to reaching the subcutaneous fat and, since skin is a scattering medium, incident light is also scattered and reflected from the patient's skin, resulting in a very small fraction of the incident light reaching the subcutaneous fat. Therefore, due to both the small fraction of the applied energy reaching the subcutaneous fat and the low absorption of this energy by the fat, in order to get enough energy to the subcutaneous fat at these wavelengths to be effective, large amounts of radiation would need to be applied to the overlying epidermis and dermis. Since such high levels of radiation absorbed in the dermis or epidermis would cause significant thermal damage to these skin layers at the prior art wavelengths, treatment/destruction of fat cannot be performed through the skin, but must be performed by providing an opening, for example a surgical opening, through the skin to provide direct contact with the fat tissue to be treated. Even when the radiation is applied directly to the fat tissue to be treated, high energy is required and great care must be exercised to avoid excessive radiation of surrounding or underlying tissue so as to minimize damage thereto. Other prior art fat treatment techniques, involving the use of either microwaves or ultrasound, either alone or in conjunction with liposuction, to melt or loosen the fat and to remove it or have it absorbed into the body, have either proved not to be effective for fat removal, have posed potential health hazards to patients, either actual or perceived, or have still involved invasive procedures, the risk of which have been discussed earlier.
A need therefore exists for an improved technique for heating and destroying, or otherwise targeting lipid-rich tissue, including, but not limited to, subcutaneous fat, sebaceous gland, lipid in membrane cells and fat covering anatomical elements on which surgical or other procedures are is to be performed, which does not suffer the limitations of prior art techniques, including liposuction, and which is significantly more selective than the prior art in the destruction of lipid-rich tissue over tissue containing water so as to safely achieve the desired effects on lipid-rich tissue in performing a therapeutic procedure.